Meshed Network Without Parallel Line - ABB Relion 650 Series Applications Manual

Section 6
Current protection
Only detailed network studies can determine the operating conditions under which the
highest possible fault current is expected on the line. In most cases, this current appears
during three-phase fault conditions. But also examine single-phase-to-earth and two-phase-
to-earth conditions.
Also study transients that could cause a high increase of the line current for short times. A
typical example is a transmission line with a power transformer at the remote end, which can
cause high inrush current when connected to the network and can thus also cause the
operation of the built-in, instantaneous, overcurrent protection.
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ),
UBase ) and ( SBase ).
(
OpMode : This parameter can be set to 2 out of 3 or 1 out of 3 . The setting controls the
minimum number of phase currents that must be larger than the set operate current
operation. Normally this parameter is set to
protection is to be used mainly for multi phase faults,
IP>> : Set operate current in % of IBase .
StValMult : The operate current can be changed by activation of the binary input ENMULT to
the set factor
IP>>MinEd2Set : Minimum settable operate phase current level in % of IBase, for IEC 61850 Ed.
2 settings.
IP>>MaxEd2Set : Maximum settable operate phase current level in % of IBase, for IEC 61850 Ed.
2 settings.
6.1.3.1

Meshed network without parallel line

The following fault calculations have to be done for three-phase, single-phase-to-earth and
two-phase-to-earth faults. With reference to figure 27, apply a fault in B and then calculate the
current through-fault phase current I
source impedance values for Z
get the maximum through fault current from A to B.
~
IEC09000022 V1 EN-US
Figure 27: Through fault current from A to B: I
Then a fault in A has to be applied and the through fault current I
figure 28. In order to get the maximum through fault current, the minimum value for Z
maximum value for Z
66
StValMult .
fB
and the maximum source impedance values for Z
A
I
fB
A
Z Z
A L
IED
have to be considered.
A
1 out of 3 and will thus detect all fault types. If the
2 out of 3 should be chosen.
. The calculation should be done using the minimum
B
Z
B
Fault
fB
1MRK 505 355-UEN A
IP>> for
in order to
B
~
IEC09000022-1-en.vsd
has to be calculated,
fA
B
Application manual
M12915-9 v7
and the